elytrum

The elytrum, plural elytra, refers to the hardened forewings of beetles and earwigs. In beetles, these modified wings serve as protective coverings for the delicate hindwings, which are used for flight. When a beetle is at rest, the elytra meet in a straight line down the dorsal midline of its abdomen. During flight, the elytra are typically held out to the sides, allowing the hindwings to unfurl and engage in aerial locomotion.

The structure of the elytra can vary significantly between beetle species, reflecting adaptations to different environments and lifestyles. Some elytra are smooth and shiny, while others may be sculptured with intricate patterns of grooves, punctures, or ridges. The coloration of the elytra also displays a wide range of diversity, from dull browns and blacks to vibrant metallic hues. This variation can serve purposes such as camouflage, mimicry, or species recognition.

In earwigs, the elytra are much shorter and broader than those of beetles, covering only the base of the abdomen. The hindwings of earwigs are also more complex, often folded fan-like beneath the elytra. While beetles are the most prominent group possessing elytra, the term is also used for similar structures in other insect orders, although it is most commonly associated with Coleoptera. The evolutionary development of the elytrum is considered a key characteristic of the beetle lineage.